Global System for Mobile communications (Groupe Spécial Mobile, or GSM) is the most popular standard for mobile phones in the world. One of many services provided by GSM allows a mobile device user to connect to, and browse, the Internet or other networks, such as the user's corporate Intranet. The system that provides the packet based Internet connections within GSM context is the General Packet Radio Services (GPRS) system. This system is used by GSM for transmitting data in a form of the Internet Protocol (IP) packets.
The GPRS Core Network, also known as Packet Switched Core Network, is the centralized part of the GPRS system. A connection between a mobile device and the Core Network is provided by a Radio Access Network, a part of a mobile telecommunication system that implements a radio access technology.
Typically, every GSM mobile subscriber is afforded the capability, known as roaming, to automatically make and receive voice calls, send and receive data, or access other services, including home data services, when traveling outside the geographical coverage area of the home network, by means of using a visited network. The differentiation between a home network and a visited network is technically given by the type of subscriber entry in a specific network. If a subscriber has no entry in the home subscriber register of the network, the required subscriber data is first requested by the visited network, e.g., from the subscriber's home network in order that the subscriber can be authenticated and any authorization for using the network services can be checked.
When a roaming subscriber desires to access data services, the session of the mobile device with the Internet or other data network is established through a visited network Mobility Anchor node (server), a GPRS Roaming Exchange (GRX), and a home network Gateway node (server). The GPRS Roaming Exchange facilitates exchanging data messages between a visited network and home network using GPRS Tunnel Protocol which allows end users of a GSM network to move from place to place while continuing to connect to the Internet as if from one location. Thus, a data message originated by a roaming subscriber at the visited network, gets transmitted all the way from the visited network through GRX and on to the home network before exiting to the Internet or other data network. However, it could take a long time to complete this data traffic route due to great geographic distances between locations of home and visited networks, and therefore, data traffic efficiency may be adversely affected. This is particularly relevant in a case of real-time data traffic used in Voice Over IP (VOIP) messaging, where each voice data packet has to travel all the way to the home network before being routed to the correct destination.
A more efficient approach to routing data messages initiated in a visited network is to utilize the capabilities of the visited network itself, so that the visited network serves as a “proxy” for the home network. This concept would allow users to perform at least a number of functions on the visited network, that are ordinarily done on the home network, such as, for example, charging, statistics generation, accessing third-party networks, or legal interception. The concept requires a selection of a particular gateway node (server) in the network (a “Proxy Roaming Gateway”) on the visited network that would serve as Roaming Gateway node for the data traffic. The Roaming Gateway node would proxy roaming traffic on to the home network for such purposes as, for example, charging, statistics generation, and/or legal interception.
However, the exact mechanism, which the Mobility Anchor node (server) would use to select a particular Proxy Roaming Gateway in the visited network, has not been developed. Therefore, there is a need for a method by which a Roaming Gateway can be selected for roaming subscribers accessing data services.